Manufacture of filaments for incandescing electric lamps.



No. 683,085. Patented Sept! 24, l90l.

W. L. VUELKER. MANUFACTURE OF FILAIENTS FOB INCANDESCING ELECTRIC LAMPS.

(Application filed July so, 1900.

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NrTED STATES PATENT OFFICE.

\VILLIAM LAWRENCE VOELKER, OF LONDON, ENGLAND, ASSIGNOR TO THERON CLARKCRAWFORD, OF NEW YORK, N. Y.

MANUFACTURE OF FILAMENTS FOR INCANDESCING ELECTRIC LAMPS.

SPECIFICATION forming part of Letters Patent N 0. 683,085, datedSeptember 24, 1901.

Application filed July 30, 1900. Serial No. 25,337. (No specimens.)

T0 at whom it may concern:

Be it known that I, WILLIAM LAWRENCE VOELKER, a citizen of the UnitedStates of America, residing at 42 Bernard street, Russell Square,London, England, have invented new and useful Improvements in theMannfacture of Filaments for Incandescing Electric Lamps, (in respectwhereof I have applied for a patent in Great Britain, to bear date June22, 1900, No. 11,344,) of which the following is a specification.

This invention relates to the manufacture of carbid filaments fromthreads or fibers of some carbonizable material capable of absorbing orotherwise taking up the salt of the met-alsuch asuranium,titanium,zirconium, or beryllium-which is to be combined withthe carbon in the formation of the carbid.

In the accompanying drawings, Figure 1 is a vertical section of acrucible adapted for the reception of the spooled thread or filamentduring the carbonization of the filamentous foundation and theconversion of the metallic salts into oxids. Fig. 2 is a verticalsection of apparatus for use in passing the carbonized thread orfilament through an electric arc. Fig. 3 is a corresponding plan, andFig. 4 a side View, of the upper portion of the said apparatus. Figs. 5and 6 illustrate in elevation and plan a multiple-electrodearc-producing device.

In carrying out my improved process any kind of homogeneous fibercapable of being converted into carbon by the aid of heat may beemployed-as, for example, a long-fiber cotton thread or a filamentformed by forcing cellulose while in a viscous condition through a die.The thread or filament having been rendered chemically clean in any ofthe ways known to chemists is soaked in a solution of the salt or saltsof the metal or metals intended toform the metallic base of the carbid.The salt or salts should be of a readilydecomposable kind, such as theacetate or cyanid. Aftersoaking the thread or filament is well dried andthen spooled. Where the salt has been prepared with a mineral acid andacts deleteriously on the carbon at a high temperature, the thread orfilament should be ammoniated in order to convert the salt into an oxid.

The spooling of the thread or filament may be conveniently effected on acylinder of paper, a strip of thin rice-paper being interposed betweeneach layer as it is wound on. The required. quantity having been wound,the spool is placed in an oven and well dried at a temperature whichwill not char the thread or filament. The spool is then placed in acrucible and well packed with powdered sugar-carbon and with powderedcarbid of the kind to be produced.

a is the spool of thread or filament, and b the cylinder of paperwhereon the same is wound. The spool is arranged in the crucible c-upona hollow core at, formed integral with the crucible. The object of thehollow core is to insure a proper distribution of the heat about thespool and to prevent unequal shrinkage of the filament, the cruciblebeing placed upon a kind of grid 6 with a view to facilitating access ofthe heated gases to the central duct formed by the hollow core d. Thecrucible having been carefully sealed by means of the coverf is thenplaced ina suitable furnace -such, for instance, as that known tometallurgists as an American gasfurnace or a Siemens regenerativefurnaceand the temperature gradually raised to an intense white heat,with the effect that the filamentous foundation becomes carbonized andthe metallic salts converted into oxids. The furnace having been allowedto cool slowly and the spool removed therefrom,

the end of the carbonized thread or filament is next passed through twolongitudinally- -perforated carbon electrodes 9 h, mounted axially inline with one another and capable of being moved apart, or severalcarbon pencils may be arranged about a central passage through which thefilament is led, (see Figs. 4 and 5,) the carbons being connected insuch a manner as to produce a multiple arc. The space to be occupied bythe arc is in either case immediately surrounded by a cylinder 6,composed of the metal intended to form the metallic base of the carbidor composed of the carbid itself, this cylinder being in turn inclosedwithin a tight-fitting globe or vessel 70, formed of glass or of thesame substance as the cylinder. A small electric arc is struck betweenthe extremities of the carbons 9 7a, so as to produce a highheatingeffect without much pressure, the globe or vessel 70 being meanwhilecharged with hydrogen or carbureted hydrogen or with vapor of ahydrocarbon or of the metal intended to form the metallic base of thecarbid. The spool a is preferably mounted in a gas-tight container 1, towhich the hydrogen or other gas is admitted by way of a cock m, the saidgas passing from the container Z through the perforation in the carbonit into the interior of the cylindert' and globe or vessel 70. Theextremity of the carbonized thread or filament having been passedthrough the carbon electrodes and carried to a drum or reel '27,, thethread or filament is drawn through the electric are at a speeddepending upon the strength of the current. The carbid resulting has ametallic appearance, and although of a highly-crystalline nature maywhen out into the required lengths be readily bent into horseshoe formand mounted in incandescing-lamp globes in the ordinary manner. Thetemperature which should be employed at the final stage of convertingthe filament into carbid will vary slightly when working with differentkinds of metals. The temperature appropriate may, however, be determinedby that at which incipient fusion of the metallic oxids takes place.

The function of the cylinder '1' is twofoldfirst, to retain the heatgenerated by the elec trio arc, and, secondly, by vaporization of thesubstance of the cylinder to furnish the metal to be combined with thecarbon of the filament in the formation of the carbid. The hydrogen orother gas admitted into this cylinder becomes charged with the vapor ofthe metal composing the cylinder, the latter being thus conveyed to thecarbon of the filament and combining therewith forms, under theinfluence of the intense heat of the electric are, a carbid. The gasesmentioned may, so far as regards their mechanical functions, beconsidered as equivalents. The gas serves in every case to displaceoxygen and at the same time to convey the base metalin the form of vaporto the carbon of the filament. This function prevails whether themetalliferous vapor be supplied as such or whether it be obtained byvaporizing the surrounding cylinder. From a chemical point of View,however, the several classes of gases mentioned cannot be regarded asequivalents. It is well known that hydrogen is a powerful The carbons g71 may be mounted in asimilar manner to those in an ordinary electrio=arc lamp and their regulation effected by suitable mechanism or by hand.In the accompanying illustrations the carbon 9 is held in a socket 0,carried by a transverse bar 19, the latter being supported by rods 1 q,while the carbon his carried by the plate 7", in which thesupporting-rods s s terminate.

The method of manufacture hereinbefore described is well adapted for usein the production of incandescing-lamp filamentspvhere uranium,titanium, zirconium, or beryllium, either singly or in combination, orin combination with other metals, is employed as the metallic base ofthe carbid.

What I claim as my invention, and desire to secure by Letters Patent,is-

The herein-described method of producing carbid filaments for electricincandescin g lamps, consisting in soaking a long-fiber cotton thread orcellulose filament in a solution of a readily-decomposable salt orsaltsof the metal or metals intended to form the metallic base of the carbid,drying and spooling the same, packing the spool with powdered carbon andcarbid of the kind required in a sealed crucible and subjecting the sameto a temperature adapted to convert the salt or salts into oxid oroxids, passing the filament thus carbonized through an electric arcwhile surrounded by a cylinder or like envelop composed of the aforesaidmetallic base and inclosed within a vessel charged with hydrogen or likegas incapable of supporting combustion, substantially as set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

WILLIAM LAWRENCE YOE llltElt.

Witnesses:

PERCY E. MATTOCKS, IRENEO FRAN. VELHo.

